Double pipe chiller



Feb. 1,1944. B. F. KUB'AUGH v 2,340,759 l DOUBLE PIPE CHILLER Filed Nov. 2, 1942 2 sheets-sheet 1 llli i grwa/Mio'o HI frzzbauyb Febl, 1944- B. F. KUBAUGH DOUBLE-PIPE CHILLER 2 Sheets-Sheet 2 Filed Nov. 2, 1942 Patented Feb. 1, 1944 UNITED STATESy PATENT OFFICE (Cl. (i2-141) 5 Claims.

This invention relates to double pipe chillers of the type comprising a stack of substantially horizontal pipe sections connected in serpentine series for conducting a liquid to be chilled, the horizontal pipe sections being provided with connected jackets constituting the evaporator elements of a refrigerator system for absorbing heat from the liquid owing through the inner pipe sections.

In double pipe chillers as heretofore known, the ends of the inner and outer pipes have been united to the serially adjacent respective inner and outer pipes by headers having an inner conduit joining the inner pipes and an outer conduit joining the outer pipes. In such a construction it was practically essential for the liquid refrigerant traveling serially through the outer rpipes to enter each outer pipe section at one end and to exit at the opposite end. Likewise, it was practically necessary to place the outlets for gaseous refrigerant at one end of each outer pipe section.

A double pipe Chiller so constructed and arranged .is not efficient to an optimum extent, for the long path of travel of the liquid refrigerant from one end to the other of the outerpipe sections, and the progressively increasing gas pressure from the inlet to the outlet ends of the outer pipe sections above the liquid refrigerant in said -pipe sections generated through ebullition throughout their entire length, progressively depresses the gradient of the surface of the liquid in said pipe sections in the direction toward the discharge end, resulting in a progressively diminishing heat exchanging efficiency.

One of the objects of the present invention is to weld the outer pipe sections to the inner pipe section, thus avoiding the necessity for header connections between the ends of the outer pipe sections. This makes it practicable to interconnect the adjacent pipe sections at both ends and to admit liquid refrigerant at both ends by way of said connections. It also makes practicable the provision of a gaseous refrigerant discharge at the middle of each outer pipe section. These two factors of improvements have the effect of cutting in half the distance through which the liquid and gaseous refrigerant must travel within the outer pipe sections and correspondingly increases the heat exchanging efficiency of the apparatus.

Other objects of the invention will appear as the following description of a preferred and practical embodiment thereof proceeds.

lIn the drawings which accompany and form a part of the following specication and throughout the several gures of which the same characters of reference have been employed to designate identical parts:

Figure 1 is a view in side elevation of a double pipe chiller embodying the improvements of the present invention;

Figure 2 is an end elevation of the same;

Figure 3 is a fragmentary detail in longitudinal section showing the slip joint connection between the inner and outer pipe sections at one end of the latter.

Referring now in detail to the several figures, the numeral I represents in general the innerpipe system which comprises the straight pipe section 2, substantially horizontally disposed, and as shown, arranged in side by side vertical banks with the pipe sections of each in horizontal adjacency. At one end the vertically adjacent pipe sections 2 are connected by the vertical return bends 3 in vertically staggered relation, while at the opposite ends the horizontally adjacent pipe sections are connected by the horizontal return bends 3. Thus, a serpentine conduit is provided with the straight pipe sections in serial relationship so that the liquid to be cooled, entering the conduit at the lower end 4, passes rst serially through the lowermost horizontal pipe sections,

, then upwardly through the next horizontally adjacent pair of pipe sections, and so on until it discharges from the conduit at the upper end 5.

The straight inner pipe section 2 is jacketed by the straight outer pipe section B in annular spaced relation thereto and welded at one end as at l to the inner ypipe section 2, which it surrounds. Due to the necessity for providing for differential thermal expansion between the inner and outer pipe sections it is impossible in practice to weld both ends of the outer pipe sections to the surrounded inner pipe sections, so a slip joint is provided for each outer pipe section at the end opposite the welded end. Such a slip joint is illustrated in Figure 3, in which the outer pipe section 6 is provided with a flanged end I3 having an enlarged counterbore 8 forming an interior shoulder 9 for receiving the compressible packing rings I0 and the metallic ring I0. A flanged follower I I surrounds the inner pipe section 2-, having a portion I2 of such diameter as to permit it to enter the counterbore B and to press the packing rings II), expanding them into sealing relation between the inner and outer pipe sections. The follower is designed to be tightened toward the packing rings I0 .bymeans of bolts passing through bolt holes I4 in the fiange of the follower and screwing into threaded sockets I5 in the flanged ends of the outer pipe section. Thus, relative movement between the inner and outer pipe sections due to differences in temperature between the inner and outer pipe sections is permitted without setting up strains in said pipe sections.

Referring to Figures l and 2, it will be observed that the vertically adjacent outer pipe sections of each vertical bank of double pipes are laterally connected at both ends by the liquid refrigerant overflow conduits I6, alternately for the respective banks, and that the horizontally adjacent outer pipe sections of said banks are connected at both ends by equalizing conduits Il. Each of the overflow conduits I6 at its upper end commu.-

nicates with the associated jacket at the upper part of said jacket, determining av normal liquidV level in both horizontally interconnected jackets,

leaving space above the liquid level for the gasof the lowermost jacket and an upper connection 23 to the gaseous refrigerant atmosphere of the jacket system so that conditions in the iloat chamber and the jacket system are the same and the liquid level in the iloat chamber is the same as that inthe lowermost jackets of both banks. The iloat control of the liquid refrigerant prevents flooding of the jacket system in a manner well known.

The mode of distributing liquid refrigerant through the jackets is as follows. Entering one of the top jackets from the upper end of they supply conduit !8, the liquid refrigerant owssimultaneously through the equalizing conduits Il at both ends of said jacket, entering the horizontally adjacent jackets at both ends and lling both jackets concurrently until the liquid level in each reaches the upper ends of the overow conduits I5 at both ends of one of said jackets, thence flowing downward' through said overflow conduits, entering the next underlying jacket at both ends, and so on until the lowermost pair of jackets have been supplied,` the liquid level being maintained constant in these by the float controlled valve I9.

Thus, the liquid refrigerant entering the `jackets of the double pipesections at both ends has only half the distance to travel, as contrasted to the older constructions in which it was supplied serially to the jackets, entering at one end, traveling through the entire longitudinal extent of the jacket and discharging at the opposite end.

At an intermediate point, preferably at the middle, each outer pipe section is connected at its top toa gaseous refrigerant outletr conduity size to produce a static conditiongof theggaseous refrigerant therein so .that anyI liquid'refiigei'- tia ant incidentally entraned with the vapor flow ing through the outlet conduits 24 and headers 25 and 26 is separated in the accumulator, dropping to the bottom thereof and being returned to the topmost jackets by the conduit 29, which loops below the liquid level in several of the upper jackets so as always to contain a liquid seal.

It is apparent that by having the gaseous refrigerant outlets at the middle point of the refrigerator jackets, the discharge gradient of the liquid surface in the several jackets inclnes from both ends toward the middle and will be much closer to level than in those constructions in which the vapor pressure progressively rises from theinlet end of thejacket to the outlet end. A greater measure of refrigerating efficiency is thus secured. A

The invention further contemplates a system of drain connections at one end of the refrigerating jackets whereby any pair of horizontally adjacent jackets may be drained. The drain connections comprise branch pipes 3| connectedinto the horizontal equalizer conduits I1 at one end of the jacket system, each branch pipe having a cut-olf valve 32. The branch pipes communicate with a common drain discharge pipe 33. In normal operation all of the valvesare closed and the liquid refrigerant is compelled to use the overflow conduits I6 in flowing from one pair of jackets to a lower` pair. When it is desired to drain any pair iof horizontally adjacent jackets, therefrigerant supplyfcut-off valve 34 is closed andthe cut-off valve 32 associated with the pair of jackets to be drained is opened, the

other cut-off valves remaining closed. The liquidf refrigerant will be heldin those jackets which are not being drained.

While I have in the above description disclosed what I believe to be a preferred and practical.

embodiment of the-invention, it will be understood to those skilled in the art that the details of construction and arrangement as described are illustrative of a practical form of the invention but not to beconstrued as limiting the scopev of the appended claims.

What I- claim is:

l. Double pipechiller comprising a serpentine coil in the form of a bank of superposed jacketed straight horizontal pipe sections, serially con-- nectedat opposite` ends providing-a conduit for theiow of liquid to be cooled, means serially connecting saidl jackets at both ends, said means including overflow pipes establishing communication between each jacket and the one next below having their upper ends above the bottom of the higher jackets whereby a liquid level is established in each jacket, means communicating with the top jacket for supplying liquid refrigerant to said jackets and a gaseous refrigerant outlet from each jacket at a point adjacentthe middle and above the liquid level therein.

2.. Double pipe chiller comprising -a serpentine coil inthe form of side by side banks of superposed jacketed straight horizontal pipe sections, serially connected at opposite ends providinga conduit for theow of liquid to be cooled, corresponding sections of` each bank being in horizontal 'adjacency, means serially connecting-the jackets at both ends comprising equalizingl connectionsV between the lower parts of horizontally adjacent jackets and overflow pipes establishing communication between each pair of horizontally adjacent jackets and. the pair next below, having their upper ends above the bottom of thehigher lished in each horizontally adjacent pair of jackets, means communicating with a jacket of the topmost horizontally adjacent pair for supplying liquid refrigerant to said jackets, and a gaseous refrigerant outlet from each jacket, at a point adjacent the middle and above the liquid level therein.

3. Double pipe chiller comprising a serpentine coil in the form of side by side banks of superposed jacketed straight horizontal inner pipe sections serially connected at opposite ends providing a conduit for the ow of liquid to be cooled, corresponding sections of each bank being in horizontal adjacency, means serially connecting the jackets at both ends comprising equalizing connections between the lower parts of horizontally adjacent jackets, and overflow pipes establishing communication between each pair of horizontally adjacent jackets and the one next below, having their upper ends above the bottom of the higher pair whereby a liquid level is established in each horizontally adjacent pair of jackets, the jackets each comprising an outer pipe section surrounding the corresponding inner pipe section, welded at one end thereto and having a packed slip joint between said sections at the opposite end permitting differential thermal elongation of said sections, means communicating with a jacket; of the topmost horizontally adjacent pair for supplying liquid refrigerant to said jackets, and a gaseous refrigerant outlet from each jacket at a point adjacent the middle and above the liquid level therein.

4. Double pipe chiller comprising a serpentine coil in the form of side by side banks of superposed jacketed straight horizontal pipe sections serially connected at opposite ends providing a conduit for the flow of liquid to be cooled, corresponding sections of each bank being in horizontal adjacency, means serially connecting the jackets at both ends comprising equalizing connections between the lower parts of horizontally adjacent jackets, and overflow pipes establishing communication between each pair of horizontally adjacent jackets and the pairnext below, having their upper ends above the 'bottom of the higher pair of jackets whereby a liquid level is established in each jacket, means communicating with a jacket of the topmost p air of horizontally adjacent jackets for supplying liquid refrigerant to said jackets, gaseous refrigerant outlets from each jacket at a point adjacent the middle and above the liquid level therein, independent drain pipes from the equalizing connections at one end of each pair of horizontally adjacent jackets and a. cut-off valve in each drain pipe.

5. Double pipe chiller comprising a serpentine coil in the form of side by side banks of superposed j acketed straight horizontalpipe sections serially connected at opposite ends providing a conduit for the ilow of liquid to be cooled, corresponding sections of each bank being in horizontal adjacency, means serially connecting the jackets at both ends comprising equalizing connections between the lower parts of horizontally adjacent jackets, and overow pipes establishing communication between each pair of horizontally adjacent jackets and the pair next below, having their upper ends above the bottom of the higher pair of jackets whereby a liquid level is established in each jacket, means communicating with a jacket of the topmost pair of horizontally adjacent jackets for'supplying liquid refrigerant to said jackets, gaseous refrigerant outlets from each jacket at a point adjacent the middle and above the liquid level therein, independent drain pipes from the equalizing connections at one end of each pair of horizontally adjacent jackets and a cut-off valve in each drain pipe, said drain pipes being connected into a common liquid refrigerant return.

BENJAMIN F. KUBAUGH. 

